Concentration oe copper ores



M lg? 1929. l an HOLLADAY 1,706,293

CONCENTRATION OF COPPER ORES Filed Aug.- ll, 1926 x o AA lll 'Patentedlidar. 19, 1929.

UNITED STATES PATENT OFFICE.

JAMES A. HOLLADAY, OF DOUGLASTON, NEW YORK, ASSIGNOR TO UNION CARBID'ESALES COMPANY, A CORPORATION 0F WEST VIRGINIA.

CONCENTRATION 0F COPPER CRES.

Application filed August 11, 1926.

The invention relates to the concentration of copper ores by frothdotation, and in particular to the treatment of oxidized copperminerals, such as malachite, cuprite and chrysocolla, to render themamenable to such flotation. lt is known that only the sulphide ores ofcopper are satisfactorily fioatable, and it has been proposed to treatthe oxidized ores with acetylene to increase their floatability. Theinvention comprises improvements in the process last referred to.

'lhe acetylene can be applied in a variety of ways, and eithersimultaneously With the grinding of the ore or after grinding iscompleted. Previously prepared gaseous acetylene may be injected intothe pulp of ore and Water, or merely brought into contact with thesurface of the liquid, or a solution of acetylene in water or othersolvent may be mixed with the ore or pulp, or calcium car bide may beadded to the pulp whereupon the Water present will of course decomposethe carbide and produce acetylene.

'As an incident to several of the desirable methods of applyingl theacetylene, the ore j is subjected to the oxidizing action of atmosphericair. The air may be initially present in the Water used or it may betaken up by the Water when the latter is agitated in the presence ofair, as Where the ore is ground While the acetylene is being applied toit. My experiments indicate that the action of air is undesirable, andthat it interferes with the effect sought to be brought about by theacetylene, at least when air has unrestricted access to the pulp.Furthermore, explosive mixtures of air and acetylene may be formed inand around the grinding mills and other apparatus, and the presence ofsuch explosive mixtures is an undesirable hazard.

The invention consists in preventing or diminishing contact of theground ore with oxygen by displacing` or diluting with an inert gas theair which might otherwise act on the ore. lilue gases, or more or lesspure nitrogen or carbon dioxide, are mentioned as examples of inertgases suitable for this purpose.

The inert gas is preferably adnlixed with the acetylene in suchproportions that nonexplosive mixtures are produced. l/here theatmosphere in contact with the ore contains suflicient inert to renderit noncxplosivajthe concentration of oxygen pres- Seral No. 128,677.

ent will in general be insuflicient to interfere seriously with theaction of the acetylene on the ore.

ln the annexed drawing I have indicated on a triaxialdiagram thosemixtures of acetylene, air, and nitrogen which are nonexplosive. It Willbe understood that the explosibility of a gas mixture cannot be statedWith precision, inasmuch as it is largely influenced by the shape andsize of the vessel containing the mixture, and by the character of themeans used for ignition. An intense or fat7 spark Will ignite manymixtures which can not be ignited by a less energetic spark of the samelength. In the experiments on which the diagram is based, the gasmixtures were saturated With Water vapor at C., and were subjected tothe action of a rather thin spark l/iL inch in length while held in aspherical bulb of approximately 3 inches diameter, the spark gap beingat the center. All ignitible mixtures Were classified as explosive, eventhough combustion proceeded quietly under the test conditions. The testswere arranged with a view to simulating conditions which might arise inthe treatment of ores With acetylene.

It will be apparent that displacement of air by inert gas in accordanceWith the invention may be effected in many different Ways, depending onthe manner in which the acetylene is applied. Procedure Which has givengood results is to ilow the pulp into a ball mill arranged to be closedgas-tight or nearly so; pass nitrogen into the mill until the oxygenconcentration is sufficiently diminished; add calcium carbide Whilesubstantially preventing access of air; grind the charge; and thendischarge the mill.

I claim:

rlhe process of preparing oxidized copper minera-ls for f ath flotationwhich comprises suspending the Jfinely ground mineral in Water as apulp, treating the minera-l particles with acetylene, and preventingaeration of the pulp during the process by displacing air in contacttherewith by a noncombustible, inert gas, whereby the act-ion of theacetylene on the mineral particles is intensified.

In testimony whereof, I aflix my signature.

JAMES A. HOLLADAY.

